1. Field of the Invention
The present invention relates to liquid-ejection recording heads that perform recording operation by ejecting liquid toward recording media and to methods of manufacturing the same.
2. Description of the Related Art
In general, liquid-ejection recording heads are fabricated by bonding a recording element substrate, which includes an ink chamber and an energy-generating element for ejecting liquid, and an electric wiring member, which is for electrically connecting the recording element substrate to a liquid-ejection recording device, onto a supporting unit. Multiple electrode leads extending from the electric wiring member are electrically joined to the recording element substrate, and the joint section is sealed by using a sealant composed of a sealing material.
In the configuration of the related art, the upper side and the lower side of the electrode leads are sealed using different kinds of sealants. For the lower side, a first sealant having elasticity when cured and also having relatively high fluidity is applied so that the first sealant can easily flow into narrow gaps at the lower side of the electrode leads. For the upper side, serving as an electrical connection section between the recording element substrate and the electric wiring member, of the electrode leads, a second sealant having strong adhesive force and maintaining a rigid shape when cured is applied. By applying such a sealant, the electrode leads and the electrical connection section can be protected from external force, such as wiping force.
In such a configuration, the recording element substrate and the electric wiring member are bonded to the supporting unit, and the first sealant is poured into a region between the supporting unit and the side surfaces of the recording element substrate. The first sealant covers the lower side of the electrode leads. Subsequently, the second sealant is applied over the first sealant and the upper surface of the electrode leads so as to cover the electrode leads. Japanese Patent Laid-Open No. 2006-167972 discloses a liquid-ejection recording head that uses these two kinds of sealants.
In the method of the related art, the upper and lower surfaces of the electrode leads are covered using two kinds of sealants in this manner. One approach for achieving a simplified process and cost reduction as well as alleviating stress applied on the recording element substrate involves eliminating the sealant (i.e., the first sealant) applied around the recording element substrate. The elimination of the sealant applied around the recording element substrate is expected to achieve the benefit of alleviating the stress applied on the recording element substrate. As mentioned above, the second sealant is to have properties by which the second sealant can maintain its shape and be in a firm state when cured so as to protect the connection section between the electrode leads and the recording element substrate from external force. Due to having extremely low fluidity, if the second sealant is applied from above the upper surface of the electrode leads without applying the first sealant, it would be difficult for the second sealant to flow downward through between the electrode leads and reach the lower side of the electrode leads, resulting in a partially exposed state of the electrode leads. The exposed electrode leads coming into contact with air or ink can sometimes cause an adverse effect.
If a sealant with low viscosity is supposedly used, the sealant may be able to flow to the lower surface of the electrode leads. However, this may not be preferable since the sealant can possibly overflow when the viscosity thereof is lowered during the curing process thereof performed at high temperature, resulting in exposed electrode leads.